People....people, people please. Listen. There will be no atomic explosion.

I admit that what I initially said about the Fukushima distaster was WILDLY inaccurate. This accident has outpaced any personal conception I previously had of nuclear accidents. But this was not due to a technical misunderstanding of the mechanics behind nuclear physics. My inaccuracies were a product of grossly overestimating the safety systems.

With that being said, there is no way that an actual nuclear explosion can occur either in the core of the reactor or the spent fuel pools.

A power excursion is indeed a criticality accident. And there is the possibility of an actual nuclear power excursion occurring. And that may produce a large explosion. But that is not the same as a nuclear explosion.

There will be no giant nuclear mushroom clouds. There may be an explosion. But it will not be due to nuclear detonation.

What was that about the "Chicken Littles"? We chickens got severely tarred and feathered.

But thanks for admitting that your higher expectations and faith in the industry have not been fulfilled.

The more like you that turn away from nuclear towards better alternatives, the greater is the possibility that it can be stopped at this point. People like you--people who have lost faith--are key to that happening. Very important.

13. OK, I remember your post from a few weeks ago 'let's talk about nuclear reactors'

Edited on Thu Apr-14-11 03:08 AM by pa28

Maybe that was not the exact title but it was something along that line. You posted a nice OP when events proved you wrong which deserves some credit but how can you authoritatively say what will happen now when no controls are left and events are now nothing more than a live experiment?

It's true that there will never be a mushroom cloud "atomic explosion" but I sometimes wonder about the possibility of an atomic "fizzle". I'm certainly no expert and my layman's mind imagines one critical mass falling on another critical mass creating a small detonation that spreads material into the environment. Maybe you can explain why this is impossible.

I saw a documentary on Chernobyl and the engineers on the scene were worried about such a possibility when they were examining the melted mass in the basement of the reactor building. Maybe they were wrong.

Here's another story with commentary from an engineer concerned about the same thing. Maybe he's wrong too.

Amazing how many wrong things in that post:- containment domes several meters thick- there will be no explosion. - even if there was, the containment dome would stop the material from reaching the open air- etc etc etc

A second, more powerful explosion occurred about two or three seconds after the first; evidence indicates that the second explosion resulted from a nuclear excursion....However, the ratio of xenon radioisotopes released during the event provides compelling evidence that the second explosion was a nuclear power transient. This nuclear transient released ~0.01 kiloton of TNT equivalent (40 GJ) of energy; the analysis indicates that the nuclear excursion was limited to a small portion of the core.

For all intents and purposes, that was a nuclear explosion.A "nuclear transient" which releases as much energy as a small tactical nuke is a nuclear explosion.0.01 kiloton = 10 ton, which is equivalent to a small tactical nuke:

The M-388 round used a version of the W54 warhead, a very small sub-kiloton fission device. The Mk-54 weighed about 51 lb (23 kg), with a selectable yield equivalent to 10 or 20 tons of TNT (very close to the minimum practical size and yield for a fission warhead).

Large-scale (production) nuclear reactors are susceptible to prompt criticality accidents when a large amount of reactivity is added to a core, such as during the movement of control rods. Alternate mechanisms include the loss of negative reactivity, such as when hot, borated coolant water is replaced with cold, pure water in the reactor core.<1> Historically, all such accidents have been caused by control rod movements. The rapid uncontrollable increase in reactor activity in prompt critical conditions may irreparably damage the primary containment of the reactor, namely the fuel cladding. A breach in the primary containment may be further exacerbated by a failure of the secondary, tertiary, and subsequent containment, which in a typical reactor plant might include the reactor vessel, reactor plant piping, various shielding materials that surround the reactor, and finally the reactor building. Nuclear reactors are designed to make prompt criticality as unlikely as possible, while utilizing multiple layers of containment as a precaution against the release of radioactive fission products should a breach occur as a result of a reactor accident.

Your OP is overtly an attempt to clear up a misconception that few possess. A "mushroom cloud" does not necessarily evidence a thermonuclear explosion - it is characteristic of any large explosion. Every discussion I've seen is focused on the China Syndrome possibility, well known as a dirty bomb steam explosion.

It would be good to settle on terms and address "nuclear transient" directly, please, so that people aren't confused. Your response keeps sliding into "power excursion". I know you have a valid reason for that but the act of change isn't helping your somewhat tattered credibility since it looks like you are deliberately altering the parameters of what is being discussed and continuing to soft sell the dangers associated with the situation.

You might try making your case that the sudden massive release of energy you are referring to isn't the same as full criticality in a thorough, professional, descriptive presentation. It would be the proper thing to do, but I don't think it would create the effect you wish to foster.

But after running into people who thought depleted uranium was a radiological weapon and was made from used reactor fuel my confidence in people's understanding of nuclear issues isn't what it used to be.

44. A fuel-air explosion isn't always intentional - but it's still an explosion

Just because it's not intentional doesn't mean it isn't an explosion.Just because it's not confined doesn't mean it isn't an explosion.An accidental flour mill explosion is still an explosion.It's accidental and the reaction is stopped as soon as the material is heated and expands in volume.It's still an explosion.

Thermobaric explosives apply the principles underlying accidental unconfined vapor cloud explosions (UVCE), which include those from dispersions of flammable dusts and droplets.<2> In previous times they were most often encountered in flour mills and their storage containers, and later in coal mines, but now most commonly in discharged oil tankers and refineries, the most recent being at Buncefield in the UK where the blast wave woke people 150 kilometres (93 mi) from its centre.<3>

At this point your constant reposting of this crap is basically disinformation. If you won't acknowledge the difference between a criticality accident and nuclear detonation then you should step out of these threads and stop spreading fear.

...I agree that Fukushima have thrown us a few surprises, mainly huge hydrogen blasts and spent fuel pool issues. But it isn't a Strangelovian doomsday device despite all the screwups, misfortune and stupidity.

27. When white hot matter hits ground water, as it will do if left unchecked....

Edited on Thu Apr-14-11 05:13 AM by JohnnyRingo

it will explode much like if one throws molten solder in a bucket of water. The solder will turn the water into steam at such a fast rate it will fling the solder and water in all directions. If that solder is radioactive, it becomes a "dirty" bomb on a smaller scale that Fukushima.

There is no option but to stop the reaction before it gets to that point. Even if people have to die doing it.

I love how you keep attempting to discredit every bit of evidence that leads to the line of thought that this is a major catastrophe.

It *IS* a catastrophe, the public is being mislead as to the gravity of the situation, and no, you can't sit back and downplay this like it is nothing. I understand the urge to do so if you are a person that works in the industry, but that doesn't serve humanity or the public.

I am not anti-nuke, I am vociferously anti-bullshit. I'm just as pissed when I get lied to about nuclear energy as I am about anything else I get lied to about, and continuing to soft sell it and PR the consequences over are not going to make me less pissed off.

Let's hear the ugly truth and go from there, because there is a time for reality to sink in so that we can deal with it.

All I'm doing it trying to get things accurate - 'the ugly truth', if you will. That, inevitably, involves pointing out the Alex Jones is an idiot conspiracy theorist who makes his living suggesting all kinds of secret goings-on that have no basis in reality.

At no point have I suggested 'this is nothing'. But saying there were atomic explosions at Fukushima won't get us anywhere. Telling people it's worse than it is will just spread fear.

After the March 15 explosion, radiation levels rose dramatically here 100 miles south of the reactors, rising to 6-7 times normal background levels in the course of a few hours. But the levels dropped fairly quickly after that:

43. Thanks! I find it unseemly to the victims the amount of BS pouring out from this.

Edited on Thu Apr-14-11 08:16 AM by Odin2005

I keep hearing fools saying that crops here in the US will be made dangerous to eat from radiation and other such nonsense. Just because some of the radiation has blown over to here does not mean it will increase the amount of radioactivity substantially over natural background levels from the carbon-14, potassium 40, and radon in the environment.

Now for the folks in Japan it's a different matter, they are REALLY screwed!

61. It's the people in Fukushima and, to a lesser extent, northern Ibaraki

Edited on Thu Apr-14-11 10:05 PM by Art_from_Ark

who will pay the highest price for this nuclear disaster.

The 30km combined mandatory/recommended evacuation zone right now covers about 1/10 the area of Fukushima Prefecture (think of it as covering 1/10 the land area of Connecticut). They are talking of expanding that. The largest city on the cusp of that zone is Iwaki, which has a population of more than 350,000. Imagine trying to evacuate all those people.

The disaster has already severely affected food products from the area-- no one wants to buy Fukushima food products, and Ibaraki farm products are also suffering, even though the only Ibaraki farm product that has recently not passed radiation tests is spinach (according to the Ibaraki Shimbun newspaper). Of course, the fishing industry is also damaged, as are the supporting industries. Many roads are still in poor condition, and an earthquake earlier this week re-damaged part of an expressway that serves Iwaki. So those folks up in Iwaki and surrounding area are the ones who face the greatest nuclear-related risk at this time.

if hundreds of tons of super-hot molten radioactive slag comprised of the nuclear fuel, silicon and cement burns down and hits the water table?

Or the fact that all four reactors might all suffer the same fate?

It certainly appears that at least two of the four reactors' spent fuel storage pools have been destroyed, especially from HD images taken by satellite of the roofless Reactor #3.

In order to someday "bury" all four, I expect that the roofs of reactors #1 and #4 will need to be removed, and three of the four may need to have a portion of each of their four walls knocked down perhaps halfway to ensure a "proper" burial of their contents...

But who really knows how much volume, for what distance, and with what amount of force any irradiated "ejecta" in the form of steam, ash, and molten slag would be spread and propelled?

If an "eruption" or eruptions were to occur AFTER the four reactors are buried, the built-up pressure due to super-heated and radioactive steam could become enormous, causing a much more powerful explosion and eruption.

I hope that TEPCO can cool each of these reactors' contents to the point where they cannot become super-hot again, but that could take months, if not years?

The fuel heats up and the pressure builds UNDER the cladding. It will eventually relieve itself. Pieces of fuel rod were blown (some say 1 mile) into the air at Fukushima. Large fragments were found between the reactor buindings

So? Good for you for understanding nuclear physics, but you were still wrong, and pretty forceful with your pronouncements. I don't claim much technical understanding of the mechanics behind nuclear physics (some, but not much). Yet I knew the potential for disaster from the moment the plant was reported as damaged.

People with a wonderful grasp of theory can be very arrogant. I am not directing this at you personally, nor am I trying to demean those who have a grasp of theoretical physics. I admire that greatly. I also applaud you for being able to admit you were wrong. But very bright people often seem to believe that because they are smarter than almost everyone else, in the theoretical realm, they must therefore be right more often than everyone else, in other realms as well.

Wrong.

"In theory, theory and reality are the same; in reality, they're different." (--me)

Theory will never encompass reality with all of its messiness and variables that we cannot control. That is why I believe we should not be playing with nuclear power: we can control it just fine, as long as everything goes along smoothly. It is indeed a triumph of theoretical physics and practical engineering. But then along come external realities -- things like materials stress, terrorists, human error, natural disaster, the depredations of time, the politics of renewing nuclear plant licenses after their built-in lifetime has expired -- to name just a few messy aspects of reality that are not necessarily amenable to tidy theoretical analyses. So I do not blindly trust the judgment of theoreticians, however brilliant, to properly assess the risks to the rest of us, especially when the risks are as high and as long-lived as they are with nuclear materials.

because I took the time to look at the actual evidence and read the actual scientific data available relating to loss of cooling accidents at boiling water reactors, while others who were very loudly proclaiming their scientific genius were satisfied to simply deride anyone who doubted the happy talk as being "hysterical" and uneducated.

I put up with a lot of insults from the know-it-all crowd, but I was right. The situation was far more dangerous than officials were letting on. Cooling was not sufficient. Fuel rods were damaged. Melting, fragmentation and re-criticalities did occur.

Some people have earned credibility here, others have lost it. Maybe you can learn a lesson. Hippie punching is not a viable alternative to actual scientific inquiry.

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